


Claimed Innocence

by Mistress_of_Undertail



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell, Both Sans and Papyrus are Kids, F/M, Fontcest, Incest, M/M, Noncon Fontcest (but unwilling), Noncon with Minors, Slavery, Underage Sex
Language: English
Status: In-Progress
Published: 2018-05-15
Updated: 2018-05-15
Packaged: 2019-05-07 07:29:20
Rating: Explicit
Warnings: Rape/Non-Con, Underage
Chapters: 1
Words: 3,185
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14666277
Author URL: https://archiveofourown.org/users/Mistress_of_Undertail/pseuds/Mistress_of_Undertail
Summary: (Inspired bythis plot bunnybyaskellie. Link contains spoilers, but there will be massive changes, especially for the ending.)In the Underground, it’s not just kill or be killed. It’s…Own or be Owned.Weaker monsters can be protected if they are willingly (or unwillingly) publicly claimed by stronger monsters, giving them a way to survive in a cruel and unforgiving world.Orphans Sans and Papyrus struggle to keep themselves alive, despite Sans' unparalleled power making him one of the most feared monsters in the Underground at the tender age of 13. But his baby brother wasn't so lucky. Instead, he was gifted a rare innocence and compassion for all life. Still, in a world where kindness is weakness, and weakness gets you killed ...or worse, Sans will have to do the unthinkable in order to keep him safe.





	Claimed Innocence

 

“No! Let me go!”  
  


Papyrus struggled against the monster’s hold. The pig monster lifted him up easily with one hand, the tips of Papyrus’ worn boots barely scraping the ground.

“Heh! Aren’t you a cutie?” He brought a fat, pink finger to Papyrus’ jaw, lifting his chin as Papyrus continued to pull against the sweaty fist wrapped around his wrists. “Only skin an bones! Well, scratch the skin, eh? BHWAHAHHAH!”

He burst into laughter, showering Papyrus with spit and his putrid breath. Sheer panic twisted Papyrus’ soul. He’d never been caught like this before. He’d always been so careful.

Sans had gone off to search for food and he had decided to go exploring as usual. Most monsters ignored him and if they didn’t, he was usually too quick, running circles around them until they gave up or lost sight of him. But Papyrus had grown so much this past year, his arms and legs longer now, wrists and ankles easier to snatch.

His attacker - a walking, talking pile of pork flesh - shoved him against the nearest trash heap, slamming Papyrus’ skull against an old cooler. Blinking away stars, he felt the weight of the monster’s arm against the top of his shoulders, pinning him against a lumpy black trash bag. Papyrus could feel the cold air against the back of his ribcage as his shirt was yanked up.

“Ooo. Nice bones you got there. So smooth…” The pig snorted against his skull and Papyrus shuddered in revulsion as something wet and slimy brushed against his neck. A calloused palm pressed against his spine, sliding down to the back of his shorts and slipping inside to fondle his tailbone. “I know you got more than that down here. Come on. There’s no one here, but if you play nice, I’ll take care of you real good.”

Papyrus cried out as his shorts were violently shoved down to his ankles. His knees shook so hard they rattled as a cold, nauseating shiver ran up his mistreated spine. He couldn’t move with the monster’s weight on his back and his legs barely kept him upright.

“Please…please don’t…” he whimpered, struggling not to cry. “P-please…”

“Oh, poor baby. Don’t be scared. Big Ham here will show you the ropes. If you show me a good time, I’ll even keep you.” The pig pressed his wet nose to his cheek, kissing and licking his jaw. “Then no one will ever fuck with you again. Wouldn’t you like that? Yeah, you would. Wouldn’t you, baby? So just…ngh…”

Papyrus’ entire body locked up, paralyzed with sheer horror as he felt something rub against his sacrum. He tried desperately not to think, not to understand what was happening. He didn’t want to know. He could barely breathe, he was so scared.

Then it was over.

One moment the monster was over him, a suffocating weight breathing down his neck, then it was gone, replaced with the cool air of Waterfall and the fresh stench of rotting trash that it carried. Papyrus scrambled for his shorts, pulling them back up and spinning around.

His assailant was flailing in the air, his chest glowing a deep blue. He was huge, a round ball of pink sweaty flesh and stubble, barely clothed by the stained shirt and unzipped leather pants that stretched over his massive waist. His thick arms and legs flapped about, like he was struggling to fly.

“SANS!” he bellowed, his pig face a block of crimson. “YOU ASSHOLE!”

Papyrus blinked and looked down, finally spotting his brother only a few yards away. His eye glowed an angry crimson under the shadow of his jacket’s hood, illuminating the pure fury on his face. His hand was stretched out, fingers spread wide apart. The pig monster only had time to spew a few more obscenities before he was slammed violently against the invisible edge of his brother’s barrier. Papyrus flinched, the monster gasping loudly as all the air was punched out of his massive lungs.

Sans didn’t give him time to take even half a breath. He waved his arm and the pig flew as commanded. Up, down, left, right, left, up, down. Sans slammed him again and again and again, his arm a blur of motion, until he brought him down into the polluted water that pooled at their feet and kept him there. The pig monster gurgled and struggled under the magical weight, but it was no use. His movements got more frantic and Papyrus realized Sans wasn’t going to let him up until he was dust.

“No! Sans!” Papyrus pushed himself to his feet and raced to him, throwing his arms around him from behind. “Please! Let him go! Please, Sans! It was my fault, I wasn’t careful enough! Please don’t kill him! Please! Don’t do it!!”

“Tch!!” Sans scowled and Papyrus could feel every bone in his brother’s body tense with rage, before finally Sans brought his hand up and his eye stopped flashing.

The pig monster’s head shot up from the water, sputtering and coughing as he swallowed huge gulps of life-giving air.

He was still cursing. “YOU MOTHERFUCKING CHEATING SON OF A WHORE! JUST YOU WAIT! I’LL SNORT YOUR DUST, YOU PATHETIC PIECE OF SHIT.”

Papyrus pressed face against his brother’s back, just below his shoulder blades, the highest he could reach. Sans made another frustrated sound, but he placed one hand over his wrapped around his chest.

“You okay, bro?” he asked, ignoring the insults still being screamed at him.

Papyrus nodded against his back. “I’m okay. …Let’s just go. Please.”

Sans nodded, and turned around, taking him by the shoulders.

Behind him, the pig monster had gotten to his feet, a torrent of disgusting water running off his body. “Fuck you Sans!! Why don't you just claim the little fucker already if you care so fucking much, you fucking pansy! You can't fucking watch him forever, you fucking bitch ass pussy! You’ll see! If not me, it’ll be someone else! HAH! I can’t fucking wait to see your face! Serves you right, you dumb piece of shit!”

Sans’ fingertips dug into Papyrus’ collarbone as the pig monster erupted into snort-filled, bawling laughter. Papyrus could hear his brother’s teeth grind together as he began to turn towards the pig again.

“Don’t!” Papyrus whispered, gripping his sleeve. “Please. Lets just go. Please? Brother?”

Sans hesitated for only a moment, before he let out a loud, aggravated sigh. He teleported them out of Waterfall, taking them to the blistering cold of Snowdin where they were hardly any safer, the pig’s laughter echoing after them.

 

 

***

 

The next morning, Sans woke up to the sound of his little brother preparing breakfast.  


Their current living situation involved hiding in a cave deep inside the sheer mountain outside Snowdin. Its narrow opening was only wide enough for monsters their size to squeeze through, keeping them safe during the night. The chamber itself barely had enough room to house them comfortably. One day, they’d outgrow the place. It was cold and shitty, but it was better than living without a roof above their heads. Sans wasn’t looking forward to it…again.

A small fire sat beside him, warming him where he lay on a large piece of cardboard he and his brother shared for their bed. Sans didn’t get up right away. Instead, he turned his head to watch Papyrus sitting at the cardboard box that served as their table. His brother was cutting up a crabapple into four careful slices then sliding them onto two sharpened sticks.

When did Papyrus get so big? Sans’ baby brother had turned ten only a few weeks ago and Papyrus did look it when he was kneeling - slim chested with a child-sized skull. But as Sans watched Papyrus stand to his full height to carry his sticks to the fire, the child disappeared. He could easily have passed for twelve or thirteen. He was getting so tall.

Papyrus knelt down again, tucking his scuffed boots under him as he hovered the pieces of crabapple over the flame, toasting them. He hummed softly as he worked, a gentle smile on his face.

Sans’ soul throbbed with a sick longing and he pulled his jacket’s hood down over his eyes, gritting his teeth.

He was so gross.

“Wake up, lazy bones!” his brother finally said. “It’s time to eat!”

Sans pushed himself up then, putting more effort into his slapped on grin. "Morning, bro."

“Good Morning!” Papyrus beamed at him (the sight making Sans’ soul ache) and handed him his crabapple stick.

Running the heel of his free hand against his chest to sooth the feeling away, Sans shuffled over, sitting next to him by the fire. "Thanks."

The food was gone in two bites. There was more crabapple left, but it was all they had and food had been more scarce than usual lately. They had to save it.

Luckily, the hunger pangs weren’t so bad anymore, having gotten used to them by now. Sans was relieved Papyrus was finally old enough to understand. It had been so hard back when he’d scream and scream whenever he was hungry and there was nothing Sans could do about it. It seemed like only yesterday his brother needed help getting dressed. Now he was cooking breakfast. How did this happen? Time slipped away so fast.

As he reminisced, Papyrus shifted closer, leaning his skull against his arm. Sans tensed, praying his brother couldn’t feel the uptick of his soul’s pulse at their sudden proximity. “H-hey, bro. What’s up?”

Papyrus shrugged tightly, glancing to the side. His smile went slack. “I…I’m really sorry about yesterday. I don’t know how that happened. I’m usually so good at not getting caught! And…thank you. I…I don’t know what would have happened if you hadn’t been there.”

In the wretched world they lived in, it seemed absolutely impossible that someone as sweet and loving as Sans’ little brother could exist. Despite the warmth that spread over him from Papyrus’ words, they also reminded him of how close he had been to not being there in time, to arriving too late and that disgusting creature would have…

He buried the thought.

Or tried to.

“Of course, bro. I’ll always be there,” he said, even as yesterday’s events started to replay in the back of his mind.

“You can't fucking watch him forever… If not me, it’ll be someone else!”

Sans closed his eyes, shivering with revulsion. Never again. No one will ever get that close to Papyrus again.

Over his scattered dust.

He felt the warmth of his brother’s soul as Papyrus slipped his arms around his chest, practically sliding into his lap to get close. Sans slipped his arms around him automatically, feeling the heat on his face. There had been a time when Papyrus had been tiny, and snuggling close had been perfectly innocent and comforting. Not anymore.

It must have been a real scare for Papyrus, wanting to nuzzle up to him like this. Well, of course it was. It had been such a close call. It was either that or his brother’s empty stomach was getting to him. Papyrus had a habit of wanting to cuddle when he wasn’t feeling good.

“It’s going to be okay,” Sans murmured, rubbing a line between his brother’s shoulder blades. “You can stay here today. You’ll be safe and I’ll be back in no time with more food, okay? I have a good feeling about today. Something will turn up, I know it.”

Papyrus nodded, pressing against his chest. “Okay.”

Sans raised his hand to his brother’s skull, running his thumb back and forth soothingly. Could he protect him forever? Or was it inevitable that he'd fuck up? His soul twisted painfully at the thought. He hugged Papyrus tightly for a moment, pulling him properly into his lap, nuzzling his neck. Papyrus wrapped his arms around his shoulders, shifting easily to accommodate his neediness.

God, it wasn’t fair. Why did Papyrus feel so good in his arms like this? They were brothers. He practically raised him and he was so young. He shouldn’t be having these thoughts, these desires. And yet…yet…

Sans pulled back a little, looking down at him. Papyrus tilted his head back, eye-lights bright and curious. "What is it, Sans?"

His face burning, Sans glanced to the side as he wondered…

"Has anyone ever kissed you? …On the mouth?"

That pig had gotten too far with his brother. Who knows if this had ever happened before and Papyrus just didn’t tell him about it? His brother wouldn’t have if he knew it would upset him. Once, Sans had noticed scuffed elbows and knees that Papyrus insisted were from his own clumsiness, but Sans knew better. Papyrus was one of the most agile and careful monsters he’d ever known. Like hell he tripped and fell.

So, what if…

What if he had already been too late?

Papyrus' eyes widened before he glanced to the side, his cheeks glowing. “N-no,” he said, shaking his head. “No… I… Yesterday had been the closest, but… No, I haven’t done…that with anyone before.”

"Can I kiss you?"

The words spilled out of Sans’ mouth before he could stop them. Inside he was screaming. This was so wrong. This was disgusting. What was he doing?! Papyrus was his little brother! He was only ten!

...But then he remembered yesterday. It was a miracle nothing happened. The very thought made him sick.

At the very least, he was giving him the freedom to choose, to say no, if that’s what he wanted. Sans wanted to make Papyrus’ first kiss mean something. …But he'd be lying if he said he didn’t want this for himself too.

Papyrus' stared wide eyed surprise at him. His blush deepened and his shocked gaze turned thoughtful.

Good. Sans was grateful for that at least. It wouldn't count if Papyrus just blindly agreed to whatever he asked of him. He wanted his brother to freely choose, to think about it. That was the whole point. And maybe he’d refuse, maybe…

Papyrus smiled as he nodded. “Okay.”

Sans could barely breathe as Papyrus raised his face, looking at him expectantly as he slipped his hands around his neck. He must have watched the couples make out in the bushes in Waterfall a little too closely for Sans’ comfort. Sans could feel his brother's soul flutter nervously against his ribs, and yet there was no hesitation, no uncertainty. Only absolute trust.

"Close your eyes," Sans whispered, voice shaking.

After Papyrus obeyed, Sans took a breath and kissed Papyrus gently on the teeth, gathering him close. Papyrus pressed their chests together, mirroring the gesture. The warmth of the connection spread throughout Sans’ bones, making him tremble. Slowly, he dragged his teeth a little across his brother’s, the magic that lined their bones humming at the contact. Papyrus shivered in his arms, tightening his grip on his jacket.

After a moment of this, Sans lost himself.

He wanted more.

He brought a hand to his brother’s cheek, running a thumb along his jaw. Applying a gentle pressure, he guided Papyrus’s mouth open and slipped his tongue inside. He licked just beyond Papyrus’ teeth, slow at first. His soul pounded at his own audacity, afraid he was taking this too far, even as he moaned at his brother’s taste, at his warmth.

If Papyrus didn’t like it, he didn’t show it. Instead he followed Sans’ lead, bringing forth his own tongue and pushing clumsily against his with a soft sound that made Sans’ lower half squirm.

He tightened his grip, running a hand up the back of Papyrus’ neck at the base of his skull. As the kiss lengthened, Sans grew more bold. He played with his brother’s tongue with his own, sliding and twirling them together. Papyrus gasped and tried to keep up, his tongue pressing back eagerly, drool running down both their chins.

Finally, Sans drew back to catch his breath, staring half-lidded at his brother. Papyrus met his gaze, mouth still open. He grinned.

It was infectious.

“You liked that?” Sans asked, rubbing his back with a grin of his own, a real one.

Papyrus nodded, his grin widening and before Sans could say another word, his brother yanked him down, bringing their mouths together again. Sans never could say no to him, so why would he now? He returned his brother’ overly enthusiastic kiss, hands on his brother’s hips to keep him in his lap as Papyrus pulled so hard he nearly toppled them over.

They laughed between kisses, a bubbling happiness Sans didn’t expect erupting from his chest.

Surprisingly, Sans was the one to end it. “Paps! Wait..ha... We-we can’t just do this all day…”

“Aw, why not?” Papyrus asked, rubbing his face against Sans’ jacket and effectively wiping off his wet teeth against it. Sans didn’t mind.

But before he could answer, both their souls rumbled loudly with hunger. Papyrus’ grin turned sheepish and Sans felt another rush of affection at the sight of him.

“That’s why.” Sans kissed the crown of his brother’s head, and gently pushed him off his lap.

Sans was just relieved he hadn’t gotten too heated up. It wouldn’t have been the first time, but he’d always managed to hide it from Papyrus. That was one conversation he didn’t want to have yet, though he was sure Papyrus had some idea. It was hard to stay completely naive when monsters were out fucking in the very alleyways they scavenged.

Papyrus wiped his mouth against his sleeve, his face still red. Sans blushed too, though couldn’t help but feel giddy. It wasn’t what he had expected to feel.

“Did you like that?” he asked him again, the edges of his smile pulled tight.

Papyrus nodded, beaming. “It was fun. Like tongue wrestling!”

Sans laughed, feeling a renewed surge of love and affection for him. “…Okay, I should get going then, before all the good food is gone.”

“Oh. Alright.” Papyrus’ grin was still in place, but it was clearly not as sincere as it had been a moment ago. “Be careful. Don’t get lost. I’ll clean up and make dinner. And think of a bedtime story for tonight. Don’t be late!”

Sans saluted. “Aye, aye, boss. I’ll leave the fortress in your mighty fine hands. Keep it safe.”

He waited till Papyrus saluted back, the stars back in his eyes, before Sans squeezed through the narrow tunnel leading to the ledge of the cliff their cave sat on.

It wasn’t until he was away from his brother’s warmth and back into the cold, dark reality of his life, did it finally dawn on him what he had done.

Sans kissed Papyrus. He kissed his ten year old brother. He even used tongue. And Papyrus let him. Papyrus even liked it! A lot!

He was absolutely the worst brother. The most disgusting, despicable, wretched…  


What was he going to do?! Sans had to protect him. But who was going to protect Papyrus from him?

**Author's Note:**

> [My NSFW 18+ Undertail Tumblr](https://mistressofundertail.tumblr.com/)
> 
>  
> 
> I love comments, reactions, asks, constructive criticism, etc.
> 
> Don't be shy. I don't bite. <3


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